This is a multicenter, open-label, safety trial of azimilide in patients who have completed a previous trial of azimilide as a treatment for atrial fibrillation, atrial flutter or paroxysmal supraventricular tachycardia (protocol D87). The only subjects who are eligible are those who have successfully completed protocol D87 by having a documented recurrence of an index arrhythmia or by finishing 270 days of followup without having a symptomatic recurrence. Patients will take the dose of azimilide that was used in their previous randomized clinical trial once a day, 100 mg per day. During the trial, patients will return to the clinic at Week 1 and at Months 1, 2, 4, 6, 9, 12, 18 and 24, and then every 6 months for up to 3 years for evaluation of safety parameters.